Fire protection system with a variable pressure floor

ABSTRACT

A fire protection system employing a plurality of extinguishant discharge heads located in the space to be protected and adapted to open in response to a predetermined fluid pressure and deliver extinguishant to the fire. The pressure for opening one or more heads varies from the pressure for opening other heads.

United States Patent [151 3,684,023

Cham a me 1 An 15,1972

[54] FIRE PROTECTION SYSTEM WITH A lilltienn l,I 1)1;

VARIABLE PRESSURE FLOOR y en et 3,309,028 3/1967 Zieg etal ..169/l6 X [72] Inventor: Carol Z. Champagne, Rockland,

Mass. Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Thomas C. Culp, Jr. [73] Asslgnee' 523 22 xgg zz corpora Attorney- Lane, Aitken, Dunner& Ziems [22] Filed: June 8, 1971 [57] ABSTRACT [211 App]. No.: 151,014 A fire protection system employing a plurality of extinguishant discharge heads located in the space to be protected and adapted to open in response to a [52] US. Cl ..l69/ 16, 169/37 predetermined fluid pressure and deliver extinguisham Int. ..A62c to the fire 'rha pressure for opgning one or m [58] Field of Search ..l69/5, 16,37 h ads varies from the pressure for opening other heads. [56] Hermes CM 13 Claims, 3 Drawing Figures UNITED STATES PATENTS 1,958,286 5/1934 Tyden ..169/l6 PATENTEUMIG 15 um ENTOR CAROL z. CHAMPAGNE 6 r I WQMMQMWYZM w ATTORNEYS FIRE PROTECTION SYSTEM WITH A VARIABLE PRESSURE FLOOR BACKGROUND OF THE INVENTION Automatic sprinkler systems for protecting industrial V and commercial properties normally employ thermally releasable sprinkler heads located near the top of the space being protected. The sprinkler heads are supplied with a suitable extinguishant, such as water, by a pipe network of mains, risers, cross-mains and branches. Most sprinkler heads used in these type systems have a discharge opening or throat normally cal pattern of droplets simulating the characteristics of I rain.

Because of the high degree of head standardization, design parameters for automatic sprinkler systems have, in the past, been limited to a selection of head release temperatures, head spacing and system supply capacity, including pipe sizes and the like. In the selection of a head release temperature it has been conventional practice to select sprinklers with higher temperature ratings than those which wouldrespond quickly to the existence of a fire in the protected space. Although such a delayed response is sometimes undesirable, the disadvantages are outweighed by such advantages as avoidance of accidental release and potential loss by water damage, and the avoidance of heads located remotely from the actual fire being actuated by the effects of convention and the circulation of hot combustion products throughout the protected space. This latter factor is believed to be one of the principal causes for failure of automatic sprinkler systems, particularly in the case of intense high challenge fires where all available extinguishant is needed on and near the burning fuel surfaces to bring the fire under control.

The selections of head spacing and water supply capacity for water sprinkler systems are predicated largely on the required water density needed to extinguish the most intense fire anticipated, as well as on economic considerations. For example, since the maximum amount of extinguishant capable of being delivered by one head is relatively fixed by the size of its discharge orifice, increased densities have been achieved in the past by overlapping the floor areas to which extinguishant is directed by each of the heads. In other words, where increased densities are called for, the number of heads employed in the system is increased and the spacing between heads reduced to achieve overlapping coverage. The capacity of the water supply required to supply such heads has in the past involved the application of conventional principles of fluid flow, taking into account the flow requirements of all of the sprinkler heads when operating under the conditions presented by the most destructive fire which is anticipated.

Although automatic sprinkler systems of the type described have been an effective means for the protection of property against loss or damage by fire, the trend during recent years to higher storage enclosures coupled with the increased use of plastics has presented new challenges for such systems. For example, recent extensive studies with actual and synthetically produced fire plumes or columns have shown that in the enclosed spaces of 20 feet and higher, the updraft or chimney effect caused by convention alone is sufficient to prevent the free falling water droplets produced by conventional sprinkler heads from penetrating the rising fire plume and reaching the burning fuel surfaces. Because of this phenomenon, such sprinkler systems merely operate to wet down or inhibit the spread of a high challenge fire within the space and thus provide what is referred to as exposures protection. However, the temperatures reached in a high challenge fire are sufficient to effect a self-drying of the fuel supplying the fire. Moreover, where the fuel is plastic or plastic wrapped, it is not capable of being pre-wet by the sprinkler heads around the fire plume and hence burning proceeds substantially uninhibited.

Another factor to be accounted for occurs where the heat of a localized high challenge fire establishing a fire column or plume in excess of 20 feet in height flares out beneath the ceiling of the protected space and actuates numerous sprinkler heads located at such a distance from the fire that they are ineffective to deliver water or other extinguishant to the fuel surfaces. This contributes not only to redundant and flooding use of the water, but more significantly, robs water from the heads over the fire where it is needed to extinguish the fire.

It will be apparent, therefore, that conventional automatic sprinkler systems, though adequate for the protection of buildings and other spaces with relatively low ceilings, are less effective in high challenge fire situations where there is adequate ceiling height for a strong intense fire plume or column to develop.

In U.S. patent application Ser. No. 102,652 filed on Dec. 23, 1970, by William L. Livingston, and assigned to the same assignee as the present application, a fixed fire extinguishing system is disclosed which is designed to limit the number of sprinkler heads which will be activated by a fire. The heads are spaced apart greater distances and have large outlet orifices to enable greater quantities of water or other extinguishant to be delivered from each head at lower flow rates. Preferably, the heads are in the form of wide angle spray nozzles which develop a downwardly directed spray having large size droplets as compared to the droplets produced by the conventional sprinkler heads.

With this arrangement, the first head actuated by the fire has a much better possibility of extinguishing the fire, because of the increased ability of the larger droplets to penetrate the fire plume of a high challenge fire. If the heat of the fire spreads, additional heads are actuated to help the first nozzle fight the fire and wet down areas surrounding the fire to provide exposure protection to inhibit the spread of the fire. However,

the additional heads which are allowed to be actuated heads actuated is achieved in accordance with the above-mentioned application by establishing a pressure floor so that a minimum pressure must exist at each head before it will open. The system is designed so that this minimum pressure will not be reached until a predetermined number of heads have been actuated.

In establishing the above-mentioned pressure floor, an expellable plug normally blocks the outlet of the head and is adapted to be expelled from the head to permit extinguishant flow therethrough upon the fusing of a conventional temperature responsive device and the presence of a fluid pressure in the head of a magnitude exceeding a predetermined value. In establishing the latter value a connector, preferably in the form of a thread, is utilized to maintain the expellable plug in a closed position. The design is such that the extinguishant pressure in the head acts upon the plug in a manner to place the thread in tension and to break the thread and permit release of the plug when the pressure reaches a predetermined value. Although this arrangement resulted in several advantages, including increased fire-fighting capability, significant cost savings, and increased predictability with respect to the finite fluid pressure required to enable the plug to be dispelled from the head, it suffered from one disadvantage. In particular, due to friction losses occuring in the system, the pressure available at each head in the system varied in proportion to the amount of piping extending between the particular head and the source of fluid extinguishant. Therefore, the pressure at the heads in a relatively remote position with respect to the extinguishant source was relatively low, while the pressure at the heads in the immediate vicinity of the extinguishant source was relatively high. Since all of the heads were adapted to open in response to the same pressure, this rendered it virtually impossible to achieve a uniform head opening pattern, and therefore placed limitations on the predictability of the system.

Although it was initially proposed to attempt to balance the piping system hydraulics to get uniform flows and a predictable head opening pattern, this became extremely cumbersome and almost prohibitive to a high-volume design concept.

SUMMARYOF THE INVENTION It is therefore an object of the invention to provide a fire protection system of the above type in which friction losses in the system are compensated for in order to achieve a predictable uniform head opening pattern.

It is a further object of the present invention to provide a fire protection system of the above type in which the pressure for opening one or more of the discharge heads in the system varies from the pressure for opening other heads.

Towards the fulfillment of these objects, the system of the present invention comprises a plurality of extinguishant discharge heads located in the space to be protected, means for connecting said heads to a source of extinguishant, and control means responsive to a predetermined extinguishant pressure for permitting said heads to open and extinguishant to be discharged therefrom, the predetermined extinguishant pressure for permitting at least one of said heads to open being different from the predetermined pressure for permitting at least one other of said heads to open.

BRIEF DESCRIPTION OF THE DRAWINGS Reference is now made to the accompanying drawings for a better understanding of the nature and objects of the present invention. The drawings illustrate the best mode presently contemplated for carrying out the objects of the invention and are not to be construed as restrictions or limitations on its scope. In the drawings:

FIG. 1 is a perspective view of the fire protection system of the present invention shown installed in a building;

FIG. 2 is a vertical cross-sectional view of a discharge nozzle utilized in the system of the present invention; and

FIG. 3 is an enlarged partial view similar to FIG. 2 and showing a detail of the nozzle of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The system of the present invention is shown installed in a building 10 in FIG. 1, with the roof of the building being omitted for the convenience of presentation. The system includes a source 12 of extinguishant, such as water, which is connected to a line 14 having a riser portion 14a. The line 14 connects with a submain l6, and a plurality of parallel branch lines 18 are disposed along the submain 16 at spaced intervals. It is understood that the submain l6 and the branch lines 18 are all fastened relative to the ceiling of the building 10 at a slight distance therefrom.

A plurality of extinguishant discharge heads,

preferably in the form of direct discharge nozzles, are shown diagrammatically in FIG. 1 by the reference numeral 20. The nozzles 20 are disposed at spaced intervals along each branch line 18 and extend throughout the entire structure to be protected, with the locations of the nozzles of each branch line being staggered relative to the location of the nozzles of the adjacent branch lines. A nozzle 20 is shown in FIGS. 2 and 3, and comprises a cylindrical body 22 having an upper end portion which is internally threaded as shown at 14 for connection to a source of extinguishant, and a lower end portion which defines an outlet orifice 26 of a reduced cross-section. A pair of spiral vanes 28a and 28b are fixed within the body 22 for imparting a swirling motion to water flowing downwardly therethrough in a conventional manner. The vanes 28a and 28b support a hollow central hub 30 which, in turn, slidably supports a rod 32 having a piston head 34 fixed on its lower end. A pair of sealing rings 36 and 38 are positioned about the periphery of the head 34 and sealingly engage the inner wall of the body 22 near the outlet orifice 26.

The rod 32 is latched in the position shown in FIG. 2 by a rod 42 which slidably extends through an externally threaded boss 44 projecting from the side of the body 22. One end of the rod 42 extends through the vane 28a and the wall of the central hub 30 into a slot 46 in the rod 32 to latch it in the position shown in FIG. 2.

A sleeve 48 is threaded on the end of the boss 44. The outer end of the sleeve is closed off by an externally threaded stub shaft 50 having a ring or yoke 52 thereon. The rod 42 slidably extends through the stub shaft 50, and the other end of the rod engages a conventional thermal fuse element 54 positioned within the ring 52. The fuse element 54 prevents movement of the rod 42 to the right as viewed in FIG. 2, until the heat of a fire fuses the element 54 so that it collapses. Since the element 54 is the standard type commonly used in conventional sprinkler heads now on the market, it will not be described in greater detail.

The rod 42 has a piston head 56 mounted thereon which slidably engages the internal wall of the sleeve 48. A spring 58 is positioned between the boss 44 and the piston head 56 to bias the piston head and the rod 42 to the right with a predetermined biasing force.

With this arrangement, the piston head 56 and the rod 42 will be driven to the right under the action of the spring 58 upon the fuse element 54 collapsing in response to the heat of the tire and thus unlatch the rod 32. 1

As better shown in FIG. 3, a thread 60 is provided which has one end fastened to the upper end of the rod 32. The thread 60 extends through an opening 62 formed in the upper vane 28a and the otherend of the thread is fastened to the top surface of the latter vane. The above-mentioned fastening may be achieved in any conventional manner, such as by the use of epoxy or the like. The thread is preferably of a nylon material and its length is selected so that it will have a slight slack therein in the position of FIGS. 2 and 3 to avoid any unwanted tension being placed thereon due to slight dimensional variations of the other components of the nozzle.

Referring again to FIG. 2, a fusible nut 66 is located at the discharge end of the body portion 22 adjacent the plug 34, to provide a safeguard against expulsion of the rod 32 in the event that the fusible element 54 is inadvertently actuated. The nut 66 also prevents an accumulation of dirt and grime in the discharge opening which might otherwise affect the expulsion of the plug 34 from the body member 22 in the event of tire.

As stated above, the pressure available to each nozzle varies in response to its distance from the source of extinguishant due to the friction losses in the piping. Referring to FIG. 1 for an example of this, it can be appreciated that the pressure available to the nozzles along the branch line 18a will be less than that available to the nozzles 20 along the branch line 18b, for example, due to the increased friction losses occurring by virtue of the extinguishant flowing a greater distance down the submain 16 in its travel to the branch line 18a than to the branch line 18b. Assuming equal actuation pressures for each nozzle, this is undesirable, since, as a result of the friction losses, the nozzles along the branch line 18b would be actuated before the nozzles along the branch line 18a.

Therefore, according to a feature of the present invention, the nozzles located more remote from the source of the extinguishant are adapted to be actuated by pressure lower than the nozzles closer to the source of extinguishant in a manner so that a uniform head opening pattern will be achieved. To this end, the nylon threads 60 associated with the nozzles 20 are sized so that the tension required to break them and therefore release their respective plugs, varies in accordance with the location of the head.

As an example of the foregoing, the nozzles 20 along a particular branch line 18 would incorporate nylon threads of a diameter which is smaller in proportion to the distance of the branch line from the intersection of the line 14 with the submain 16. As a result, the nozzles further away from the line 14 will be actuated in response to a lower pressure acting on their plugs than the remaining nozzles. Assuming a spacing of 15 feet between adjacent branch lines 18, a preferred design would incorporate a difference of 1 pound per square inch actuation pressure to all the nozzles along adjacent branch lines. Thus the nozzles 20 along the branch line would be adapted to respond to pressures of 1 pound per square inch less than the nozzles along the branch line 18b, and the nozzles along the other branch line adjacent the branch line 18c would be adapted torespond to a pressure of 1 pound per square inch less than the nozzles along the branch line 18b, etc. In this manner the response characteristics of each nozzle can be predicated to a substantially accurate degree, so that the system can be designed to permit an optimum number of nozzles to be opened in response to a fire situation.

Of course, for even more precise response characteristics, the actuation pressure of each nozzle along a given branch line can also be varied with respect to its adjacent nozzles depending on its distance from the submain 16, in a similar manner.

In operation, the nozzles 20 are installed in the manner shown in FIG. 2, with the rod 32 of each nozzle latched in its respective body member 22 by the rod 42, and with its thread 60 fixed to the rod 32 and the vane 18a. If both the fusible element 54 and the fusible nut 66 are thermally actuated in response to an elevated temperature in their vicinity, the tension of the spring 58 causes the rod 42 to release the rod 32 from its latched condition, and the fusible nut-66 frees the outlet orifice 26. The extinguishant pressure in each body member 22 acting on the inner end face of its respective plug 34 forces it downwardly as viewed in FIG. 2, and causes a tension to be applied to the respective thread 60 in direct proportion to the amount of pressure. The thread 60 of each nozzle 20 will fail, or break, in response to the predetermined pressure selected for each particular nozzle, depending on the location of the latter, which will release its corresponding rod 32, and therefore the plug member 34, and permit them to be discharged outwardly from the respective body member 22. If the extinguishant pressure is not sufficient to break a particular thread, the respective plug will not be expelled from the body portion despite release of the corresponding fusible element and fusible nut.

In this manner, the fire-fighting capability of those nozzles positioned immediately above the fire and over the area immediately surrounding the fire will not be curtailed, while unnecessary water damage resulting from an excessive number of nozzles being actuated at points remote from the fire will be eliminated, as discussed above, with all of this being achieved by a system design that can be predicted to a high degree.

The system of the present invention also lends itself to other advantages. For example, any unusual reductions in the main supply of water, such as those caused by a defective main gate valve, or the like, will be easily accomodated by the system of the present invention. Also, the actuation pressures for the nozzles can be scheduled to direct the fire towards or away from a particular area of the building. As an example of the latter, the nozzles directly over a particularly valuable area of the building, such as a filing room, or the like, can be scheduled to be actuated at a relatively low pressure in order to insure early actuation of the nozzles and maximum protection for the area.

It can be appreciated that several variations may be made in the foregoing without departing from the scope of the invention. For example, the nylon threads 60 may be replaced by any other suitable means which permits expulsion of the respective plugs in response to a given pressure. Also, instead of adapting each individual head to respond to a given extinguishant pressure, a pressure sensitive device can be provided for controlling a group of heads, such as all the heads along a single branch line. The pressure sensitive device could be built into the system at or near the intersection of the branch line and submain, for example, with the pressure sensitive devices nearer the source of extinguishant being adjusted to respond to a greater pressure than the devices further from the extinguishant source.

I claim:

1. A fire protection system for buildings and the like comprising a plurality of extinguishant discharge heads located in the space to be protected, means for connecting said heads to a source of extinguishant, and control means responsive to a predetermined extinguishant pressure for permitting said heads to open and extinguishant to be discharged therefrom, the predetermined extinguishant pressure for permitting at least one of said heads to open being different from the predetermined pressure for permitting at least one other of said heads to open.

2. The system of claim 1 further comprising additional control means responsive to predetermined information received from the fire for permitting said heads to open.

3. The system of claim 2 wherein said predetermined information received from the fire is the temperature at each of said heads.

4. The system of claim 3 wherein each of said heads comprises a plug for preventing the discharge of extinguishant therefrom, a fusible means normally retaining said plug in said head and responsive to said predetermined temperature for releasing said plug, and a connector normally connecting said plug to said head and responsive to said predetermined pressure for releasing 8 said plug.

5. The system as defined in claim 1 wherein said control means positively defeats the opening of additional heads when the extinguishant pressure in a predetermined position of the system reaches a certain value after a limited number of heads have been opened.

6. The system of claim 1 wherein said predetermined extinguishant pressure is a predetermined minimum extinguishant pressure at each of said heads.

7. The system of claim 6 wherein said control means includes means operatively connected to each head for permitting the opening of the head with which it is connected.

8. The system of claim 1 wherein said predetermined extinguishant pressure is a predetermine minimum extinguishant pressure in a predetermined portion of said system.

9. A fire protection system for buildings and the like comprising a plurality of extinguishant discharge heads located in a space to be protected, means for connecting said heads to a source of extinguishant, fire responsive means automatically responsive to a fire developing in said space for permitting the heads to open in a sequence dictated by predetermined information received from the fire, and control means responsive to a predetermined extinguishant pressure for defeating the opening of at least one of said heads despite the ex istence of said predetermined information, the predetermined extinguishant pressure for defeating the opening of one head being different from the predetermined extinguishant pressure for defeating the opening of at least one other head.

10. The system as defined in claim 9 wherein said control means includes control members operatively connected to saidheads, said control members being responsive to a predetermined extinguishant pressure at their respective heads for defeating the opening of their respective heads.

11. The system as defined in claim 9 wherein said control means positively defeats the opening of additional heads when the extinguishant pressure in a predetermined portion of the system reaches a certain value after a limited number of heads have been opened.

12. The system as defined in claim 9 wherein said control means is responsive to the static pressure of the extinguishant at each unopened head.

13. The system of claim 9 wherein said control means is responsive to the absences of a predetermined minimum extinguishant pressure at each head.

PO- UNITED STATES iATENT OFFIGE CERTEFECATE 0F RREMN Patent NO- 3.684.023 Dated Auguqi- 15 W27? lnventofls) Carol Z Champagne It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 35' "convention" should read convection-.

Column 2, line 5, "convention" should read --convection-.

Column 5, line 46 "nozzles 30" should read nozzles 20-.

Column 8, line 15, "predetermine" should read predeterminedm Signed and sealed this 10th day ofApril 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

1. A fire protection system for buildings and the like comprising a plurality of extinguishant discharge heads located in the space to be protected, means for connecting said heads to a source of extinguishant, and control means responsive to a predetermined extinguishant pressure for permitting said heads to open and extinguishant to be discharged therefrom, the predetermined extinguishant pressure for permitting at least one of said heads to open being different from the predetermined pressure for permitting at least one other of said heads to open.
 2. The system of claim 1 further comprising additional control means responsive to predetermined information received from the fire for permitting said heads to open.
 3. The system of claim 2 wherein said predetermined information received from the fire is the temperature at each of said heads.
 4. The system of claim 3 wherein each of said heads comprises a plug for preventing the discharge of extinguishant therefrom, a fusible means normally retaining said plug in said head and responsive to said predetermined temperature for releasing said plug, and a connector normally connecting said plug to said head and responsive to said predetermined pressure for releasing said plug.
 5. The system as defined in claim 1 wherein said control means positively defeats the opening of additional heads when the extinguishant pressure in a predetermined position of the system reaches a certain value after a limited number of heads have been opened.
 6. The system of claim 1 wherein said predetermined extinguishant pressure is a predetermined minimum extinguishant pressure at each of said heads.
 7. The system of claim 6 wherein said control means includes means operatively connected to each head for permitting the opening of the head with which it is connected.
 8. The system of claim 1 wherein said predetermined extinguishant pressure is a predetermine minimum extinguishant pressure in a predetermined portion of said system.
 9. A fire protection system for buildings and the like comprising a plurality of extinguishant discharge heads located in a space to be protected, means for connecting said heads to a source of extinguishant, fire responsive means automatically responsive to a fire developing in said space for permitting the heads to open in a sequence dictated by predetermined information received from the fire, and control means responsive to a predetermined extinguishant pressure for defeating the opening of at least one of said heads despite the existence of said predetermined information, the predetermined extinguishant pressure for defeating the opening of one head being different from the predetermined extinguishant pressure for defeating the opening of at least one other head.
 10. The system as defined in claim 9 wherein said control means includes control members operatively connected to said heads, said control members being responsive to a predetermined extinguishant pressure at their respective heads for defeating the opening of their respective heads.
 11. The system as defined in claim 9 wherein said control means positively defeats the opening of additional heads when the extinguishant pressure in a predetermined portion of the system reaches a certain value after a limited number of heads have been opened.
 12. The system as defined in claim 9 wherein said control means is responsive to the static pressure of the extinguishant at each unopened head.
 13. The system of claim 9 wherein said control means is responsive to the absences of a predetermined minimum extinguishant pressure at each head. 